Modular wide-range transceiver

ABSTRACT

The present invention provides a method, apparatus, and processor instructions for wide-range microwave communications. In an exemplary embodiment, a wide-range transceiver is made having pre-calibrated modular units including an IF radio processing card, an RF transmitter module, and an RF receiver module. Calibration factors are loaded into a memory (e.g., EEPROM) in each module during production. Certain additional calibration factors may also be loaded upon installation, such as a one time calibration for the type and length of cable connecting the RF unit to a remote SPU (signal processing unit). A processor in the RF unit is responsive to control signaling indicating a desired transmitter or receiver configuration (e.g., a particular frequency, bandwidth and modulation), to attenuate the signal in the transmitter/receiver path based on the predetermined calibration factors from the applicable modules. A method for calibrating the modules is also disclosed.

TECHNICAL FIELD

Our invention generally relates to communications systems and, morespecifically, the invention is related to the field of microwavewireless transceivers.

BACKGROUND OF THE INVENTION

Mankind has an insatiable desire to communicate. This demand has spurredon the development of a great variety of communicationstechnologies—both wired, in the form of telecommunications and datanetworks, and wireless, such as cellular, microwave and satellitesystems.

Making all these systems work together has become a daunting challenge.Back when there was only one dominant service provider—the Bell Systemin the U.S. and Canada—it was relatively straightforward to add a newtechnology to a fairly uniform network. In the case of wireless systems,the upgrades often involved a complete swap-out of the existing RF(radio frequency) units. But, the limited number of units, by today'smeasures, and fixed transceiver characteristics (e.g., a singlemodulation type), made migration far easier to plan for then than now.

Today, if a service provider wants to implement a wireless link usingmultiple modulation schemes at varying frequencies, it must typicallyresort to redundant componentry to cover the differing forms ofcommunication. For example, the main receiver path for a microwave RFunit is traditionally equipped with band pass filters, whose bandwidthis equal or slightly larger than that of the signal to be processed.This capacity dependent filter determines the sample of the receiverpath used to derive the AGC (automatic gain control) loop controlvoltage; the RSL (received signal level) strength indication issimilarly derived. Since bandwidth tunable IF (intermediate frequency)filters are expensive and immature technology, the only practical way,until our invention, in which to implement a microwave RF unit that iswide-range (by which we mean multi-capacity, multi-bandwidth, andmulti-frequency) would require a bank of IF bandpass filters. However,such filter banks, for use across many different bandwidths, are notcost effective. They also occupy significant space in the RF unit, whichdefeats a key objective of keeping the RF unit small and compact.

A different kind of problem exists when with trying to implement thetransmitter path in a wide-range microwave transceiver. In order toachieve a wide dynamic range—e.g., 40 dB accurate power control—atmicrowave frequencies, most current designs rely on open-loopcalibration methods. These typically require the RF unit to becalibrated as a whole unit, leading to complexity in the overall testsetup, increased costs, and increased test times.

In both cases, current designs fail to adequately address the problemcreated by the needs of service providers to more frequently changetheir network configurations. Whether driven by advances in technology,or changing customer requirements, a more flexible RF unit design isneeded to avoid a complete unit swap-out as newcapacity/bandwidth/frequency technologies are implemented for a givenlink.

Thus, there is a need for a better microwave RF unit design, one whichallows for flexibility and ease in implementing multiple performancecriteria (e.g., capacity, bandwidth, and/or frequency) in a low-costmanner, while still meeting all desirable and mandated regulatoryspecifications for the selected types of communications.

SUMMARY OF THE INVENTION

The present invention provides a method, apparatus, and processorinstructions for wide-range microwave communications. In an exemplaryembodiment, a wide-range transceiver has pre-calibrated modular unitsincluding an IF radio processing card, an RF transmitter module, and anRF receiver module. Calibration factors are loaded into a memory (e.g.,EEPROM) in each module during production. Certain additional calibrationfactors may also be loaded upon installation and use, such as a one timecalibration for the type and length of cable connecting the RF unit to aremote SPU (signal processing unit). A processor in the RF unit isresponsive to control signaling indicating a desired transmitter orreceiver configuration (e.g., a particular frequency, bandwidth andmodulation), to attenuate the signal in the transmitter/receiver pathbased on the predetermined calibration factors from the applicablemodules. If changes are needed for new transceiver configurations thatcannot be accommodated by software changes alone, new modules can bereadily inserted without requiring an expensive swap-out of the RF unit.A method for efficiently and economically calibrating the modules isalso disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. However, the invention itself, togetherwith certain objectives and advantages, may best be understood byreference to the following detailed description of an illustrative,presently preferred embodiment thereof, when read in conjunction withthe accompanying drawings, of which:

FIG. 1 is a block diagram of an illustrative communications system ofwhich the invention forms a part.

FIG. 2 is a block diagram of an illustrative embodiment of an RF unit inaccordance with the invention.

FIG. 3 illustrates a first IF (intermediate frequency) module accordingto an embodiment of the invention.

FIGS. 4A and 4B, respectively, illustrate transmit and receive paths ofthe IF module of FIG. 3.

FIG. 5 illustrates an RF transmit module according to an embodiment ofthe invention.

FIG. 6 illustrates an RF receive module according to an embodiment ofthe invention.

FIGS. 7A and 7B illustrate a flow chart of an algorithm for controllingtransmit path settings according to an embodiment of the invention.

FIG. 8 illustrates a flow chart of an algorithm for controlling receivepath settings according to an embodiment of the invention.

FIG. 9 illustrates a block diagram of a calibration system according toan embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The limitations of prior systems described above are overcome by thenovel improvements of our invention, which are illustrated by thefollowing detailed description of a preferred embodiment. In thisembodiment, common transmit path and receive path designs areimplemented in modular form. Despite the common designs, by using amodulation index and combining modulation/capacity correction factors, avariety of modulations (e.g., QPSK, 256QAM), capacities (e.g., 2T1,STM1), and bandwidths may be transceived without resort to redundant orexpensive circuitry. This improvement also allows for a per-moduleroom-temperature calibration process, performed during standard moduleproduction, which substantially reduces per unit production costs andfactory capital costs for testing. Moreover, by appropriate location ofattenuators, detectors, and filters, together with software control andcorrection mechanisms, the embodiment disclosed can achieve sustainedperformance across a very wide range of frequencies (over 40 dB ofaccurate power control from 3 to 40 GHz and higher).

With reference now to the figures and in particular with reference toFIG. 1, a pictorial representation of a communications system in whichthe present invention may be implemented is depicted in accordance withcertain presently preferred embodiments of the invention. Thisparticular embodiment is typical of many microwave relay designs, wherecertain components and functionality are housed in an outdoor unit (orODU 120), while others are stored remotely in more protectedenvironments (see IDU, or indoor unit, 110). Those skilled in the artwill appreciate that the invention can be readily implemented inconnection with a variety of other configurations, depending on theparticular wireless system being implemented. In particular, while thefollowing embodiment describes the invention in the context of amicrowave transmission system, it may also be advantageously implementedin most any microwave/millimeter wave frequency wireless system,including more integrated indoor-only systems, and systems where thesignal processing and radio processing are in one unit.

The indoor unit 110 is, in the illustrated case of FIG. 1, a signalprocessing unit (SPU), which includes the signal processing equipmentneeded for the microwave communications. This allows designers tominimize the equipment that has to be stored in the outdoor unit 120,closer to the antenna 125. In this case, the SPU 110 includes a MUX ormultiplexer unit 112 connected to wireline networks such as LAN 102 andPABX 105. It also includes other necessary and/or optional components,depending on the type of communications desired, such as modem/powersupply 111, auxiliary units 114, and controller 113.

The SPU/indoor unit 110 is connected to the RF/outdoor unit 120 byappropriate means such as an RG8 coaxial cable. The RFU 110 contains theIF and RF components (described in more detail below) for converting thesignaling from the SPU into an appropriate wireless signal fortransmission via antenna 125. Antenna 125 receives/transmits wirelesssignaling with other remote antennas such as antenna 126, which isconnected to further networks 140 via its local RF/signal processingequipment 130.

1. Overview of the RF Unit

FIG. 2 illustrates one embodiment of a modular RFU 120 in accordancewith the invention. Only part of the circuitry is illustrated here, andmore detailed descriptions of the individual modules are provided belowin connection with FIGS. 3 through 6. Here, the RFU 120 has beenconveniently produced in six modules, each capable of separatemanufacture and rapid placement or replacement from a given RFU. Thesesix modules are: IF/RPC (radio processing card) 200 (also shown in FIGS.4A and 4B); transmitter monolithic microwave IC (Tx MMIC) module 300(also shown in FIG. 5); receiver monolithic microwave IC (Rx MMIC)module 400 (also shown in FIG. 6); synthesizer module 500; high poweramplifier (HPA) module 510; and antenna coupling unit (ACU) diplexermodule 520. As noted above, this is an illustrative embodiment, andthose skilled in the art should appreciate that a variety of alternativeconfigurations are possible, including those either more highlyintegrated, or those using discrete components (i.e., not just IC's);and a “module” can represent everything from a single chip to amulti-card subsystem or series of boxes functioning together; thosehaving direct (cable-less) connections; and those in which the SPU andRPU (and other processing/networking) functions are fielded in one unit.

When transmitting, the signaling information is received via the cablefrom the IDU 110. This signaling information includes both the datasignal being transmitted via antenna 125, as well as certain control andtelemetry information as needed. The control information may include,e.g., instructions to a processor (CPU 208) used to control modulesettings based on the particular frequency and modulation format desiredfor a given data signal. The telemetry information also includes certainpower and alarm status information. The data signal is appropriatelyfiltered and amplified along the transmit path of RPC module 200 and TxMMIC module 300. Synthesizer module provides an appropriate localoscillator (LO) signal to mixers 225 and 310 along the transmit path.After being appropriately upconverted, the data signal is applied toantenna 125 via ACU diplexer 520 and transmitted.

On receiving a data signal, it is appropriately filtered and amplifiedalong the receive path of Rx MMIC module 400 and RPC module 200.Synthesizer module 500 provides an appropriate local oscillator (LO)signal to mixers 235 and 410 along the receive path. After beingdownconverted, the data signal is forwarded via the cable to IDU/SPU 110for further processing.

While the embodiment of FIG. 2 has been shown as a double conversiontransceiver, those skilled in the art will readily appreciate that otherdesigns are similarly useful in implementing the invention. Theimplementation chosen will be a matter of design choice.

FIG. 3 illustrates a card-level view of one possible configuration ofthe components in the IF/RPC module 200. In order to implement a modularapproach, quick connect cables and pins are used at the interfacesbetween the IF/RPC 200 components with the other modules and externalcables. Beginning with the connection to the cable from the IDU/SPU 110,a connector such as an N-type adapter J1 may be used to join the cableto a cable interface 201 or inside module 200. Other connectors to thecable interface may be used for other signaling, such as normal/fail LEDpower via J7 and AGC (automatic gain control) information via J2. Thedata signal from the SPU is provided, at a first frequency (e.g., 310MHz) to the Tx IF Circuitry 204. The Tx IF Circuitry receives an LOsignal via SMA connector J3 and, with appropriate processing applied viaradio processing card 202, outputs an IF signal via connector J4 to theTx MMIC Module 300. The cable interface 201 is also coupled with the DCpower supply 209, which provides the various designed voltages formodule componentry, and the on/off telemetry circuit 207, which furthercontrols RPC 202.

On the receive circuit, an Rx IF Circuitry 203 is provided withappropriate connections to the Rx MMIC Module 400, via J5, and a receiveIF LO signal via J6. The Rx IF Circuitry 203 is similarly coupled to theRPC 202, and its output is in turn coupled to cable interface 201.

Various other module connections are provided via pins, such as P1through P9. In one illustrious embodiment, the type of functionalityenabled might include: P1—connection to the Tx upconverter;P2—connection to the Rx downconverter; P3—control connection tosynthesizer module 500; P4—control connection to HPA 510; P5—connectionwith the module's optical ID (242 in FIG. 4B); P6—connection with themodule's EEPROM 250; P7—connection to the MHSB (monitored hot—standby)switch; P8 and P9—RF loop back switches (Tx and Rx). Of course, a widevariety of connections and connector types are possible, depending onthe design choices involved for the particular functionality desired.

2. Transmit Path

Turning now to FIG. 4A, a more detailed description of the a transmitpath of the IF/RPC Module 200 is illustrated. As discussed above, acable 205 connects to RPC module 200 and provides both data and controlsignaling to the RFU 120. The control signaling is provided to telemetryunit 207, and further applied to the routines processing in CPU 208.These routines, which are executed when implementing these embodiments,whether implemented as part of an operating system or a specificapplication, component, program, object, module or sequence ofinstructions, will be referred to as CPU programs, or simply programs.The programs typically comprise one or more instructions that areresident at various times in various memory and storage devices used inconnection with CPU 208, and that, when read and executed by one or moreprocessors, cause the system to perform the steps necessary to executesteps or elements embodying the various aspects of the invention. CPU208 can be any processor type, depending, of course, on the designrequirements of the intended applications supported by the RFU 120.

The IF transmit path includes multiple attenuators used in accuratelysetting the transmission characteristics, in order to deliver thedesired output RF signal. Two of these attenuators, AT1 (211) and AT4(214), are digital attenuators. Presently preferred attenuators wouldinclude high P_(1DB) PIN diodes in view of the high linearity theseyield, without the expense and performance issues associated withalternatives like variable gain attenuators, FET diodes and the like.The remaining attenuation is preferably applied via analog means. Thus,in a two-attenuator implementation, two DACs (digital to analogconverters), AT2 (212) and AT3 (213), are used to apply the bias to thePIN diodes, controlling the resistance value to change the RF signallevel.

In operation, the four attenuators function as follows. The firstdigital attenuator AT1 (211) functions in a closed-loop operation withthe AGC (automatic gain control) circuitry 220. Unlike the otherattenuators, AT1 need not be adjusted during operation, but is set onceduring an initialization (e.g., power-on) operation. Its purpose is tocompensate for input power variations that result from the (unknown)cable length between the SPU 110 and RFU 120. The second digitalattenuator, AT4 (214), is used for modulation index backoff. It isprogrammable according to the different modulation settings, and is usedto maintain linear operation of the transmitter path throughout all themodulations selectable. Attenuators AT2 and AT3 (212, 213) function in aclosed loop manner together with attenuator AT5 (315), IF detector 307,and RF detector 320, all of the Tx MMIC module discussed below inconnection with FIG. 5. These attenuators 212, 213, 315 combine withdetectors 307, 320 to provide closed-loop control at all powers, andfunction to compensate for any frequency, modulation, capacity,temperature, or unit-to-unit variations.

Continuing next with FIG. 5, the Tx MMIC module 300 detects the IF inputto module 300 using a power detector 307. In the illustrated case, theIF input from power splitter 305 is applied to a multi-section bandpassfilter (BPF 306), which rejects any LO leakage via mixer 310 and IFspurs that otherwise might impact power detector 307. This allows for awide range of operation, e.g., from +5 dBm to −32 dBm. Afterupconversion via mixer 310, the transmit signal is further attenuated atAT5 312. Finally, detector 320 functions to provide high and low gain RFoutput detection. Low gain detection would be appropriate, for example,with QPSK modulation (e.g., at a 10 dB range), while high gain would beappropriate for high capacity modulations like 128 QAM (e.g., at a 5 dBrange). The output of both detectors 306, 320 is provided to the RPC 202ADC, while the AT5 325 input control is from the RPC 202 DAC, inappropriate size/format (e.g., 8 bit signals in this illustration).

3. Operation of a Transmit Path

In operation, since this embodiment uses dual up-conversion, the IFsignal from the SPU 110 (e.g., 310 MHz) is first up-converted to thesecond IF frequency at mixer 210 (e.g., in a 2-3 GHz range). The datasignal is up-converted again to the desired RF output frequency at mixer310 (e.g., somewhere in the range of 6-40 GHz). The control signalingreceived at telemetry unit 207/CPU 208 is used to programmaticallyadjust the transmit path settings for the desired frequency andmodulation of the output RF signal.

On initialization/power on, the closed leveling loop of AT1 211 and AGC220 is used to account for variation in the Tx IF signal level due todifferences in the IF cabling length. The AGC 211 preferably adjusts AT1211 attenuator and switch amplifier gain to drive the associated voltagedetector to a target reference (e.g., 2V). High and low alarm thresholdmay also be used to trigger an alarm if the Tx IF detector voltage levelfalls outside these thresholds. A manual mode may also be provided forcontrol of the attenuator, e.g., for test and debug purposes.

The transmit power control process is accomplished using stored values(e.g., calibration table values stored in EEPROMs 250, 350) applied viaa transmit power control program. In a preferred process, this programis an interpolation process, using present values of frequency, dynamicrange and temperature together with the stored calibration values of theIF/RPC and Tx MMIC modules 200 and 300 to run the power controlalgorithm. Because of strict regulatory requirements the output powersettings are tightly controlled, preferably meeting a maximum of 0.5dB/10 ms and temperature sensor update every 2 seconds or so.

The Tx MMIC and IF module memories 250, 350 preferably store calibrationtables that contain the entire transmit power attenuation valuessupporting the full dynamic range (e.g., 40 dB for QPSK, for which 8 dBis achieved in the RF path and 32 dB in the IF path, in incremental (1dB) steps). The calibration tables contain the attenuator controlvoltage (a DAC value) necessary to achieve the corresponding poweroutput level, at the corresponding frequency of the table. The Tx MMICmodule 300 calibration table also contains the IF and PA detector 306,320 voltage values (an ADC value), taken during the calibration processand stored in EEPROM 350. The output power stability is maintained by anoutput power limiting window, a value dynamically calculated from RF/IFdetector curves and kept at a fixed range (e.g., +/−0.5 dB) for thewhole RF/IF detector range. The window is thus an output power and unitdependent number.

The transmit power control process is preferably implemented between twotemperature plateaus, bounding the current RFU 200 internal temperature.The resulting attenuator control voltages are then interpolated based onthe interpolation of the current RFU 200 temperature against the bounded(stored/calibrated) temperature plateaus. The computed control voltageis compensated over dynamic range, modulation, capacity, frequency, andtemperature, and is used to drive the Tx PA (power amplifier 318,represented as a single stage but which could be multistage) to a targetoutput power. This interpolation process is preferably performed atfrequent intervals (e.g., every 2 seconds), or whenever there has been achange in frequency or required Tx PA 318 level to change.

For example, given a particular modulation (such as 128 QAM) anddetected temperature (via sensor 244), the appropriate control valuestored in EEPROM 250 is used to set AT4 214 to the appropriatemodulation index backoff value. This value was previously determinedduring the calibration process (e.g., 2 dB for QPSK, while lower at 10dB for 256 QAM). Attenuators 212, 213, and 315 then operate together ina closed looped fashion with the IF and RF detectors 306, 320 to providethe desired dynamic range. In order to minimize emitted noise, theattenuators are preferably set starting with AT5 315 incrementally up toits maximum value (e.g., from 0 to 18 dB), then adding AT3 213incrementally up to its maximum value (e.g., from 0 to 15 dB), thenadding AT2 212 as needed up to its maximum value (e.g., from 0 to 30dB), to achieve the desired total range (e.g., 40 dB). The reverseprocess is used when removing attenuation, i.e., first zeroing out AT2212, then AT3 213, and finally adjusting AT5 315 incrementally down. Theinitial/minimum AT5 315 setting is preferably a fixed value over thedesired RF stage attenuation (e.g., 4+8 dB) in order to avoidoverdriving the RF PA 318.

The transmit control algorithm is further illustrated by the exemplaryflow chart of FIGS. 7A-7B. On first activating a transmit tick (i.e., aprocess timing clock beat), the requested power level is calculated andcompared against the range of RF detector 320 without amplification(steps 701-705). The high-gain switch of the RF detector circuit is sethigh or low, respectively, if the power level is in the high or lowrange, respectively (steps 709-717). The target ADC min and max valuesare then calculated using the appropriate detector table (for AGCdetector or RF detector as the case may be), and multiplied bycapacity/modulation correction factors stored during calibration. Themeasured ADC value at the detector is then compared to the targetmin/max values (steps 721-727). If the target value is in the window, aneasing or other slow convergence mechanism may be applied in singlevalue increments toward the exact target value (step 759). Otherwise,attenuation is incrementally applied or removed from AT5, AT3 and AT2towards the target attenuation setting (steps 733-755).

The transmit operation can similarly support a manual mode, for remote,test or debug purposes. Other options, such as mute (e.g., useful for upto 100 msec. after a frequency change to allow synthesizer 500 to settleout), may be automatically implemented via the control algorithm.

By using precalibrated modules 200, 300, with local memories 250, 350,temperature sensor 244, and processor 208 algorithm, this embodiment nowrealizes a fully software programmable, common path, modulation andcapacity independent wide-range transmitter. Thus, in the illustratedembodiment one is capable of satisfying stringent power controlrequirements (e.g., +/−1 dB) over a wide dynamic range (e.g., 40 dB in 1dB steps), over a wide frequency range (i.e. 37-40 GHz) within a givenband, varying modulation (e.g., QPSK up to 256 QAM) and capacity (e.g.,1.5 Mb/s (T1) up to 180 Mb/s (4DS3)), and over a wide operatingtemperature range (e.g., −33 C. to +55 C.), all in a single, modularoutdoor transceiver.

Moreover, by the use of IF and RF detectors, attenuators, and EEPROMs asdescribed above, this improved transmitter design supports module-levelcalibration. This is very advantageous, as it allows a manufacturer toavoid the expense of traditional over-temperature, over-frequency,over-dynamic range, and whole-RF unit calibration methods. This resultsin greatly reduced calibration times, test/production/manufacturingcost, and test/production-required capital investment.

4. Receive Path and Operation

The receive path of RFU 120 is illustrated in FIGS. 4B and 6. In apreferred implementation, both transmit and receive IF paths and the RPCcomponentry are advantageously located in the same module, although theycould also be implemented in plural modules.

A key problem with implementing a common path, modular, wide-rangemicrowave receiver is the in-band interference found within a widebandIF signal. This arises, for example, because the regulatory requirementsare such that systems need to meet interference requirements only withina fixed number of channels away (e.g., −30 dB C/I (carrier tointerference) within 2 channels). An RFU designed to handle only a 40MHz channel would have filters designed to handle the adjacent channelinterferers. However, if the same receive path has to handle a 3.5 MHzchannel, the interferers will fall in-band due to the greater filterbandwidth. This problem could be solved by resorting to either avariable bandwidth filter or a filter bank, but neither one of theseprovide a satisfactory solution due to the corresponding increase insize and expense from using them.

The receive path disclosed in FIGS. 4B and 6, however, enables just sucha wide-range common path without resort to filter banks or variablebandwidth solutions. It accomplishes this by the exemplary placement offilters, attenuators, and AGC and RSL (received signal level) detectors,discussed below.

Turning to FIG. 6, a received signal is first applied to the Rx RF inputof Rx MMIC module 400. Because of the variety of transmission pathinterferers and other phenomena (e.g., fading), the transceiver 120 istypically designed to retrieve signals within a wide dynamic (e.g., −20dBm to 95 dBm at the Rx RF input). But, the downconverted second IFsignal must be kept constant throughout the subsequent IF stage and SPU110 processing, and this is accomplished primarily by the closed loopformed by the AGC and attenuators AR1-AR4 231-234 in the IF/RPC 200module. In the Rx MMIC module 400, the received signal is first filteredand amplified, and downconverted via mixer 410. RF filter 426 has to bewideband, typically substantially wider than the widest of the desiredsignal bandwidths. This wide band RF filter has smaller insertion lossthan its narrow band RF filter counter part. Smaller insertion lossprovides higher system gain.

An optional attenuator AR6 436 may be used if the additional attenuationis needed, and it functions together with attenuators AR1-AR4 231-234and AGC 230 to provide the necessary closed loop control. This mayhappen, for example with 256 QAM modulated signals; in this case, AR6 isactuated when the other attenuators have reached to high levels toprovide the necessary extra attenuation and linearity. AR5 435 providesa temperature/frequency compensation, which is independent of the inputsignal level. Altogether, the Rx Module provides a designed gain (e.g.,8 dB +/−3 dB). As with the other modules, the necessary calibrationfactors for this module 400 are stored in local memory 450, which couldbe any of a variety of convenient memories, including but not limited toan EEPROM.

The first IF signal is then passed from Rx MMIC module 400 to IF/RPCmodule 200. This portion of the receive path uses one wideband IF filterbandwidth in the main path, which bandwidth is selected to be equal orslightly wider than that of the desired signal bandwidth for all thecapacities (e.g., 40 MHz). However, the AGC control voltage is derivedfrom the sample of the second IF frequency using a narrow bandpassfilter 262. Likewise, the RSL level detector circuit uses a narrowbandpass filter 248. The narrowband RSL filter is selected at anappropriate bandwidth (e.g., at 3.5 MHz) to provide rejection ofinterferers beyond the required separation (e.g., 2 channel C/I at 30dB) for the narrower bandwidth signals. By using a wideband filter 261,there may be limited rejection (if any) of adjacent channel interferencesignals when the radio is used to carry signals with narrow channelspacing. To overcome this, several independently controlled attenuatorsare deployed in several stages of the receiver path, and the IF AGCamplifier is operated below (e.g., 20 dB or more) its P_(1DB)compression point when the adjacent interference signal is not present.This ensures that the required linearity of the desired signal will bepreserved even in the presence of the strong adjacent channelinterference signals.

In order to maintain the second IF signal level constant (e.g., at 70MHz), the AGC control loop derives the AGC amplifier gain controlvoltage from a sample of the second IF signal. This IF signal may beextracted using the single, relatively narrow bandwidth (e.g., 3.5 MHz)second IF bandpass filter 262 for all the system configurations. Thus,only one calibration is required to provide accurate control voltage forthe AGC loop for all the system configurations. This is accomplished byintroducing different correction factors for different capacities, withdifferent channel spacing using modulations from, e.g., QPSK to 256 QAM.The AGC control voltage is preferably set to be proportional to the realdesired signal strength, even in the presence of strong adjacentinterference signal in the receiver path, since bandpass filter 262eliminates all the adjacent channel interference signals.

The RSL detection circuit derives the RSL indication voltage by samplingthe first IF signal (e.g., in the 1 GHz to 2 GHz range). This sample ofthe first IF signal is further down-converted via mixer 246 to a lowerIF frequency (e.g., 70 MHz) for ease of implementing the narrow bandpassfilter 247. The output of the narrow band (e.g., 3.5 MHz) filter 247 isfurther processed in RSL detector 248, which may be any of a variety ofcommercially available RSL chips. Using a single calibration inconjunction with applying correction factor for each of the differingdesired signal bandwidth and modulation levels, an accurate RSL levelmay be derived even in the presence of strong adjacent channelinterference signals.

Together, this software controlled AGC closed loop and RSL detectionprocesses make possible a wideband, capacity independent, and modulationindependent microwave RFU. By making use of a common path, costs areadvantageously held down. However, this RFU 120 can still process theRF/IF signals, for capacities ranging from 1.5 Mb/s (T1) to 180 Mb/s (4DS3) and beyond, using a variety of authorized channel spacings (e.g.,from 2.5 MHz up to 56 MHz). Depending on the capacity and the authorizedchannel spacing, different modulations are used, ranging from QPSK up to256 QAM (and beyond). The configuration of the system also allows forfull software programmability.

The receive control algorithm is further illustrated by the exemplaryflow chart of FIG. 8. On first activating a receive tick, the receivedsignal power level is calculated using RSL detector 238. This value forattenuator AR5 435 is compared to a predetermined/desired value (e.g.,in case of variations due to temperature or frequency), and if the valueis different the predetermined value is applied as the new AR5 435 value(steps 705-818). If the AR5 value is on target (e.g., within a targetwindow of 1.5 dB), the AGC detector 230 value is determined and comparedagainst corrected target AGC 230 values, the corrected values havingbeen determined by multiplying the AGC 230 detected levels bypredetermined capacity/modulation correction factors (steps 820-825). Ifthe AGC detector value is not within the target window, attenuation isincrementally applied by adding attenuation (e.g., in ½ dB steps),preferably in the order of AR1, AR2, AR3, AR6 and AR4, or removingstepped values, preferably in the reverse of the order in whichattenuation is added, until the detected value is within the targetwindow (steps 825-830).

5. A Calibration Process

Unlike prior calibration processes, the approach described here avoidsthe necessity for calibration of the radio unit as a whole. It alsoadvantageously avoids an over-temperature calibration for each unit(i.e., calibrating the whole RF unit at each temperature incrementwithin the calibration range). The need for whole-radio calibration isavoided since calibration is now done on a module basis.Over-temperature calibration is avoided by appropriate pilot andproduction sample calibration.

a. Rx MMIC Calibration

Beginning then with Rx MMIC module 400, this is the simplest module tocalibrate since the only elements needing calibration are theattenuators AR5 and AR6 435, 436. This process includes:

-   -   At a first frequency and temperature, starting with OdB        attenuation at AR6:    -   1) Set the RX input to a selected level (e.g., −30 dBm) with        minimum Rx RF attenuation (0 dB or DAC of 0);    -   2) adjust the AR5 to the predetermined total module gain value        (e.g., 8 dB), and store AR5 control DAC value into memory        (EEPROM 450);    -   3) increment AR6 (e.g., 1 dB) and store the AR6 DAC value;    -   4) repeat step 3 until calibrated across the dynamic range        (e.g., 10 dB) of AR6;    -   5) increment the frequency, and repeat steps 1-4 for each new        frequency; and    -   6) increment the temperature, and repeat steps 1-5 for each new        temperature.

In a preferred approach, step 6) is only done for a small number ofinitial (representative) units and periodic samples from a productionrun. The test temperatures do not need to be at regular intervals, aslinear interpolation can provide sufficiently accurate values so thatonly a limited number of temperatures need to be tested (e.g., at −25 C,5 C, 35 C and 70 C). When taking the values from the initial productionunits, small runs, such as 10 representative (beta, pilot or evenproduction) units will provide values that when, averaged for all units,can provide accurate table values when interpolated. It is alsopreferable to take periodic samples of a production run and perform afull calibration, as this will adjust the “master” values in response tochanged characteristics in the components (e.g., different batches,manufacturers, or the like).

When in production, a simplified process can be used to test eachmodule. First, each module is only tested at one temperature (e.g., 25 Cor room temperature is the most convenient, although similar economiesare realized if multiple temperatures are tested, but a lesser numberthan for the representative units). The values for other temperaturesare interpolated based on a comparison of the measured values versus thecurrent “master” calibration values. A pure tone (CW or continuous wave)may also be advantageously used, with moderate frequency increments(e.g., 100 MHz steps). In this manner, the time and expense of typicalunit calibration is dramatically reduced, but without loss in theaccuracy of the calibrated output of each module.

b. Tx MMIC Calibration

The Tx MMIC module 300 calibration is similarly straightforward, withcalibration being performed on both detectors 307, 320 and attenuatorAT5 315. An illustrative calibration process for attenuator 315includes:

-   -   1) adjust the Tx IF input power level to get the target output        power level (e.g., QPSK-10 dB);    -   2) adjust the AT5 control DAC value to calibrate the attenuator,        and store the AT5 control DAC value into memory (EEPROM 350, in        AT5 calibration table);    -   3) increment the Tx IF input power (e.g., 1 dB) across the        desired range (e.g., 18 dB), repeating steps 1-2;    -   4) increment the temperature, and repeat steps 1-3 for each new        temperature.

An illustrative calibration process for Tx IF detector 307 includes:

-   -   1) adjust AT5 to an initial target value (e.g., 13 dB, based on        the AT5 calibration table DAC value for the module's actual        temperature and frequency);    -   2) Adjust the Tx IF input power level to obtain a desired Pout        (module output power level, e.g., of QPSK-9 dB), and store the        detector 307 ADC value into memory (EEPROM 350, in IF detector        307 calibration table);    -   3) increment the Tx IF input power (e.g., 1 dB) across the        desired range (e.g., 44 dB, or Pout of QPSK-9 dB to QPSK-53 dB),        repeating steps 1-2;    -   4) increment the temperature, and repeat steps 1-3 for each new        temperature.

The Tx RF detector 320 may then be calibrated as follows:

-   -   1) set AT5 to an initial target value (e.g., 4 dB), and adjust        the Tx IF input power level to obtain a desired modulation Pout        (e.g., QPSK power level);    -   2) set the RF detector 320 gain control to low gain,    -   3) store the RF detector 320 ADC value in memory (EEPROM 350, in        RF detector 320 low gain calibration table);    -   4) increment the Tx IF input power (e.g., 1 dB) across the        desired range (e.g., 10 dB, or Pout of QPSK-0 dB to QPSK-10 dB),        repeating step 3; then    -   5) adjust the adjust the Tx IF input power level to obtain a        second desired modulation Pout (e.g., 64 QAM power level), and        set the RF detector 320 gain control to high gain,    -   6) store the RF detector 320 ADC value in memory (EEPROM 350, in        RF detector 320 high gain calibration table);    -   7) increment the Tx IF input power (e.g., 1 dB) across the        desired range (e.g., 10 dB), repeating step 6;    -   8) increment the temperature, and repeat steps 2-7 for each new        temperature.

In addition to these calibration measurements, one may also want todetermine and store appropriate tables for a Tx modulation index,detector 307 value for Tx IF overdriven alarm, and a Pout offset (e.g.,−1.5 dB for calibrated versus specified RFU norminal output power).

c. IF/RPC (transmit) Calibration

For each calibration, the following initialization may be used:

-   -   Step 1: apply input signal (e.g., −12 dBm at 310 MHz, at cable        interface port J3); set AT1 and AT4 at minimum attenuation (0);        set Cable Compensation Switch 219 to bypass amplifier; set AT2        and AT3 at minimum attenuation (DAC 0); unmute Tx; inject LO        (e.g., +3 dBm);    -   Step 2: store Pout level=PoutRef (dBm)

At the time PoutRef is determined, several other values may bedetermined. Thus, e.g., the Tx_Cable detector DAC value is now stored,and the range verified by comparing the variation of this value andconfirming it is proportional to the input level when stepped across aselected range. Tx mute may also be verified (e.g., confirming PoutRef<−85 dBc after mute).

The attenuator AT3 213 may be calibrated as follows:

-   -   1) initialize the module 200;    -   2) adjust AT3 until Pout decreases (e.g., at least 0.1 dB and        less then +0.2 dB), and store the AT3min DAC value (EEPROM 250,        in AT3 calibration table);    -   3) adjust AT3 until Pout decreases (e.g., to 1+/−0.1 dB), and        store the AT3 DAC value;    -   4) increment the Tx IF input power (e.g., 1 dB) across the        desired range (e.g., 15 dB), repeating steps 2-3; then    -   5) verify delta Pout (e.g., within 15+/−0.2 dB from minimum to        maximum attenuation);    -   6) store values (e.g., AT3 control DAC value into memory 250        (should be proportional to attenuation); minimum and maximum AT3        DAC value; minimum 1 dB delta AT3 DAC value);    -   7) increment temperature, repeat steps 1-6 for each temperature.

The attenuator AT2 212 is similarly calibrated as follows:

-   -   1) initialize the module 200;    -   2) adjust AT2 until Pout decreases (e.g., at least 0.1 dB and        less then +0.2 dB), and store the AT2min DAC value (EEPROM 250,        in AT2 calibration table);    -   3) adjust AT2 until Pout decreases (e.g., to 1+/−0.1 dB), and        store the AT2 DAC value;    -   4) increment the Tx IF input power (e.g., in 1=/−0.15 dB steps)        across the desired range, repeating steps 2-3; then    -   5) verify delta Pout (e.g., within 29+/−0.25 dB from minimum to        maximum attenuation);    -   6) store values (e.g., AT2 control DAC value into memory 250        (should be proportional to attenuation); minimum and maximum AT2        DAC value; minimum 1 dB delta AT2 DAC value);    -   7) increment temperature, repeat steps 1-6 for each temperature.        d. IF/RPC (receive) Calibration

There are three main calibration routines in the IF/RPC receive pathcalibration process. First, the Rx IF AGC detector 230 may be calibratedas follows:

-   -   1) set AR2, AR3 and AR4 at minimum attenuations, and set the Rx        IF input (e.g., at −80 dBm);    -   2) adjust AR1 until Rx IF output reaches a preselected value        (e.g., −14.3+/−0.1 dBm), and store the AGC ADC value (in EEPROM        250, in Rx AGC calibration table);    -   3) adjust AR1 until the Rx IF output reaches a preselected value        (e.g., −15.8+/−0.1 dBm), and store the AGC ADC value.

The Rx RSL detector 248 may be calibrated as follows:

-   -   1) set AR1 through AR4 at maximum attenuations, set the Rx RF        input (e.g., to −20 dBm), and store the Rx RSSI (received signal        strength indicator) ADC value (Rx_RSSI) and voltage        (Rx_RSSI_Volt);    -   2) adjust Rx RF input to decrease by a preselected value (e.g.,        −1 dB), and store the Rx RSSI ADC value    -   3) repeat step 2 until Rx RF input reaches a preselected value        (e.g., −87 dBm).

Finally, the Rx attenuator dynamic range calibration may be performed asfollows:

-   -   1) set the Rx RF input (e.g., to −65 dBm), and store the Rx RSSI        ADC value (Rx_RSSI) and voltage (Rx_RSSI_Volt);    -   2) set AR1 to a preselected value (e.g., 150), and AR2-AR4 at        minimum attenuations (0 dB), and store Rx IF output power level;    -   3) for a first attenuator, increment IF output (e.g., in        1+/−0.15 dB steps) until a maximum attenuation is reached (the        variation of DAC count may be 2 minimum for 1 dB of        attenuation).    -   4) compare the first attenuator's range with its operational        range;    -   5) store AR1-AR4 DAC values, maximum and minimum values, and        minimum DAC delta (e.g., for 1 dB change), into EEPROM 250.        e. RFU (multi-module) Calibration

While there is no whole unit calibration performed during production,there will be several calibrations or calculations performed when themodules are put together as an RFU 120 and powered on site. On thetransmit path, examples include: IF AGC calibration for cable lengthcompensation; IF cable alarm; nominal output power and output dynamiccontrol; PA detector alarms; power mute; and Tx IF overdriven alarm.

While one of ordinary skill in the art will understand how to implementthese, and depending on their design, other calibration processes, a fewexamples are worth mentioning. First, AT4 is used in this embodiment forthe modulation index, and calculated accordingly. AT5 contributes afirst range (e.g., 10 dB) for temperature compensation, and following(e.g., up to 8 dB) for RF close loop control. Because of the dynamicrange of RF detector, the RF close loop range is modulation dependent.

In order to maximize the usage of AT2 and AT3, there is no clearseparation between the AT2 and AT3 operation range when closed-loop withRF or IF detector. It is closed-loop with AT3 first, and then AT2 whenAT3 reaches a maximum (e.g., 15 dB) attenuation. To avoid excess highoutput power during setup, the output power level should be adjustedfrom its low level to high level. AT2 and AT3 provide a combined maximumattenuation range (e.g., 37 dB), but in addition, they may be designedto take care of some temperature variation and unit-to-unit gainvariation.

With respect to the correction factors, a Tx output power correctionfactor should be applied to correct the output power at the antennaport. One such correction factor would bePrfu=Ptxmodule+Initial Diplexer loss−L_Diplexer−L _(—) RL _(—) SW—RFAttenuation,  Eq. 1where the customer diplexer insertion loss is L_Diplexer and optional RFloop-back switch insertion loss is L_RL_SW, and an initial diplexer lossis preset (e.g., to 1.5). If the IF AGC detectors is not a true powerdetector, then a correction factor may also be needed for differingmodulations to maintain constant leveling. Finally, if the IF/RFdetector do not use a true power detector, then a correction factor willalso be needed for differing modulations for Pout display.

On the Rx path, there are two items that may need calibration orcalculation. The first of these, for RSL display, is a correction factordepending on modulation and capacity. An example of such a calculationis:RFU _(—) RSL=IF/RPC _(—) RSL−8 dB+L_Diplexer+L _(—) RL _(—) SW+AR6,  Eq.2where the diplexer insertion loss is L_Diplexer, the optional RFloopback switch insertion loss is L_RL_SW, and the RSL range is between−35 dBm to −20 dBm. Second, the AGC range may need adjustment. In thiscase, an algorithm may be implemented to determine if the Rx AGCdetector voltage is within a predetermined high-low range, and if so theAR1-AR6 values are accepted. If not, then a corresponding attenuatorvalue may be incrementally increased or decreased until the detected AGCvalue is within the high-low range.

Finally, turning to FIG. 9 a simple test set-up is illustrated. In thisillustrated set-up, a test unit 910 includes an appropriate power supplyand signal generator 911 (which, as noted above, can advantageously be apure tone generator capable of rapidly incrementing (e.g., in 100 MHzsteps) through a desired test spectrum). This unit is connected to themodule 920 being tested by convenient means, which could include manualmeans or, depending on the connectors used with the module, anyappropriate automated or quick connect unit (not shown). A measurementunit 912 is appropriately configured to capture the power and othermeasured values during each calibration test, and provide these tocontroller/processor 913 for processing or storage. Controller 913 isconfigured to run the appropriate calibration routines, based on thesignals input, set attenuator and detector values, temperature andmeasured values, and stored calibration values in memory 914, todetermine the calibration values for the module being tested. Controller913 also causes the determined calibration values to be stored in themodule's EEPROM or, when gathering representative (e.g., pilot) unitinformation, memory 914. A controlled environment 930 is also providedfor the temperature range tests of pilot modules, but would not beneeded for production modules being tested at room temperature, asdescribed above. While FIG. 9 illustrates a simple test set-up, those ofordinary skill in the art will readily appreciate that a wide variety oftest set-ups can be adapted for use in accordance with the invention,depending on factors such as the particular type and configuration ofthe module to be tested, the degree of automation desired, etc.

Thus, the present invention provides an improved microwave RF unit, andprocess for calibrating and operating such. The modular approach allowsfor simplified test/calibration during production, and ease of fieldreplacement of select modules without replacing the entire RFU. Itsunique common path design also enables use across a wide-range ofcapacities, modulations, and frequencies, providing greater flexibilityin a more cost efficient form than has previously been possible.

Of course, those skilled in the art will appreciate how a variety ofalternatives are possible for the individual elements, and theirarrangement, described above, while still falling within the scope ofthe invention. Thus, while it is important to note that the presentinvention has been described in the context of a particular doubleconversion microwave RFU, those of ordinary skill in the art willappreciate that the components and processes of the present inventionare capable of being further distributed or aggregated with others, suchas in complete wireless base stations, using any convenient modulation(e.g., FSK, ASK, OFDM), adding other functionality such as distortioncontrol, and components illustrated as if discrete in nature may, in theforseeable future, be replaced by equivalently functioning hardwareand/or software chips. The principle of room temperature calibration forproduction units, while sampling across a wider temperature (and ifdesired frequency, power) range is also applicable to a highlyintegrated single module system. Moreover, while certaintransmission-type media was particularly described, others such asdigital and analog communications links, wired or wirelesscommunications links using similar microwave transmission forms mayapply. Moreover, while the depicted embodiment is described inconnection with a microwave transceiver, the term microwave should beunderstood to encompass the higher frequency millimeter wavetransmissions, for which the advantages of our invention shouldsimilarly apply.

In conclusion, the above description has been presented for purposes ofillustration and description of an embodiment of the invention, but isnot intended to be exhaustive or limited to the form disclosed. Thisembodiment was chosen and described in order to explain the principlesof the invention, show its practical application, and to enable those ofordinary skill in the art to understand how to make and use theinvention. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Thus, it should be understood that theinvention is not limited to the embodiments described above, but shouldbe interpreted within the full spirit and scope of the appended claims.

1. A modular wide-range microwave communications unit comprising: aprecalibrated IF module having IF circuitry and an IF module memoryoperable for storing calibration values for the IF circuitry; at leastone precalibrated RF module having RF circuitry and an RF module memoryoperable for storing RF calibration values for the RF circuitry.
 2. Thecommunications unit of claim 1, wherein the precalibrated RF module isan RF transmit module comprising an RF transmit circuitry and an RFtransmit module memory operable for storing RF transmit calibrationvalues for the RF transmit circuitry.
 3. The communications unit ofclaim 1, wherein the precalibrated RF module is an RF receive modulecomprising an RF receive circuitry and an RF receive module memoryoperable for storing RF receive calibration values for the RF receivecircuitry.
 4. The communications unit of claim 1, wherein theprecalibrated IF module further comprises IF transmit circuitrycomprising plural IF transmit attenuators, IF receive circuitrycomprising plural IF receive attenuators, an IF module memory, and aprocessor and instructions, the processor being operably configured toexecute the instructions during operation of the communications unit,being operably coupled to the IF module memory and RF module memory, theinstructions comprising transmit instructions for controlling the IFtransmit circuitry based on IF transmit calibration values stored in theIF module memory and controlling the IF receive circuitry based on IFreceive calibration values stored in the IF module memory.
 5. Thecommunications unit of claim 1, further comprising a radio processingunit which comprises the precalibrated IF module and precalibrated RFmodule, and a signal processing unit having a modem, the signalprocessing unit operably coupled to the radio processing unit.
 6. Amicrowave communications system, comprising plural communications unitsof claim 5, wherein plural radio processing units are operably coupledvia wireless communications links to other radio processing units, andplural signal processing units are operably coupled via a wirelinenetwork.
 7. A modular wide-range microwave communications unitcomprising plural precalibrated modules, each having a module memoryoperable for storing calibration values for at least one of the group oftransmit IF circuitry, transmit RF circuitry, receive IF circuitry, andreceive RF circuitry.
 8. The communications unit of claim 7, wherein afirst precalibrated module comprises an RF transmit module comprising RFtransmit circuitry and an RF transmit module memory operable for storingRF transmit calibration values for the RF transmit circuitry.
 9. Theprecalibrated RF module of claim 8, wherein the RF transmit circuitrycomprises an attenuator, an IF detector and an RF detector, and the RFtransmit module memory is operable for storing calibration values forthe attenuator and IF and RF detectors.
 10. The communications unit ofclaim 7, wherein one of the plural precalibrated modules is an RFreceive module comprising an RF receive circuitry and an RF receivemodule memory operable for storing RF receive calibration values for theRF receive circuitry.
 11. The RF receive module of claim 10, wherein theRF receive circuitry comprises an attenuator and the RF receive modulememory is operable for storing calibration values for the attenuator.12. The unit of claim 7, wherein one of the plural precalibrated modulesis an IF module comprising IF transmit circuitry and IF receivecircuitry, an IF module memory, and a processor and instructions, theprocessor being operably configured to execute the instructions and beoperably coupled to each module memory, the instructions comprisingtransmit instructions for controlling the IF transmit circuitry andreceive instruction for controlling the IF receive circuitry based on IFtransmit calibration values and If receive calibration values stored inthe IF module memory.
 13. The communications unit of claim 12, whereinthe plural precalibrated modules further comprise an RF transmit moduleand an RF receive module, the RF transmit module comprising RF transmitcircuitry including an attenuator, an IF detector and an RF detector,and an RF transmit module memory operable for storing RF transmitcalibration values for the RF transmit circuitry, and the RF receivemodule comprising RF receive circuitry including a first receiveattenuator and an RF receive module memory operable for storing RFreceive calibration values for the first receive attenuator.
 14. Thecommunications unit of claim 13, wherein the IF transmit circuitrycomprises a first digital attenuator coupled to a first analogattenuator, a first mixer coupled to the first analog attenuator, asecond analog attenuator coupled to the first mixer, a second digitalattenuator coupled to the second analog attenuator, and a transmit IFAGC coupled between the first digital and first analog attenuators, andwherein the instructions are operable for controlling attenuation by theattenuators of the IF transmit circuitry and RF transmit circuitry basedon the IF and RF transmit calibration values.
 15. The communicationsunit of claim 13, wherein the IF receive circuitry comprises a receiveRSSI detector operably coupled to plural receive attenuators, the pluralreceive attenuators operably coupled to a second mixer, the second mixeroperably coupled to a further attenuator, and the further attenuatorcoupled to a receive AGC detector, and wherein the instructions areoperable for controlling attenuation by the attenuators of the IFreceive circuitry and RF receive circuitry based on the IF and RFreceive calibration values.
 16. The communications unit of claim 12,further comprising a radio processing unit which comprises theprecalibrated IF module and precalibrated RF module, and a signalprocessing unit having a modem, the signal processing unit operablycoupled to the radio processing unit.
 17. A microwave communicationssystem, comprising plural communications units of claim 16, whereinplural radio processing units are operably coupled via wirelesscommunications links to other radio processing units, and plural signalprocessing units are operably coupled via a wireline network.
 18. Amethod of microwave communications using a wide-range communicationsunit, comprising: receiving control signals at a processor of thecommunications unit from a signal processing unit, the control signalscontaining first information including a modulation and frequency value;retrieving stored calibration values from at least one of pluralmemories, the calibration values including attenuation values to be usedduring operation of the communications unit; and the processorcontrolling at least one of the group of transmit circuitry and receivecircuitry, respectively, based on the calibration values and the controlsignals to attenuate a signal being transmitted or received,respectively, at the modulation and frequency value.
 19. The method ofclaim 18, wherein the transmit circuitry comprises a precalibrated IFmodule comprising an IF memory having IF calibration values andprecalibrated RF transmit module comprising an RF transmit module memoryhaving RF calibration values, further comprising controlling attenuatorsfrom the IF module and an attenuator and a detector in the RF transmitmodule together in a closed loop to achieve a desired dynamic response,based on stored calibration values in the IF memory and RF transmitmodule memory.
 20. The method of claim 19, wherein the detector of theRF transmit module comprises an RF detector, wherein the step ofcontrolling further comprises first determining target exact, min andmax values for the RF detector based on an interpolation of storedcalibration tables in the IF memory and RF transmit module memory for ameasured temperature and selected frequency, modulation, and capacity,and multiplying the target min and max values by a correction factor.21. The method of claim 20, further comprising comparing a measureddetector value to the corrected target min and max values, and (i) whenthe measured detector value is outside the target min and max values,adjusting the attenuators one at a time in steps until the measureddetector value is within the target min and max values, and (ii) whenthe measured detector value is within the target min and max values andan easing mechanism is enabled, incrementing the attenuators one at atime to drive the measured detector value toward the target exact value.22. The method of claim 18, wherein the receive circuitry comprises aprecalibrated IF module comprising an IF memory having IF calibrationvalues and precalibrated RF receive module comprising an RF receivemodule memory having RF calibration values, further comprisingcontrolling attenuators from the IF module and an attenuator in the RFreceive module together in a closed loop to achieve a desired dynamicresponse, based on stored calibration values in the IF memory and RFreceive module memory.
 23. The method of claim 22, further comprisingdetermining target IF AGC values based on an interpolation of storedcalibration tables in the IF memory and RF receive module memory for ameasured temperature and selected frequency, modulation and capacity,and multiplying the target IF AGC values by a capacity/modulationcorrection factor to obtain a corrected target value.
 24. The method ofclaim 23, further comprising comparing a measured IF AGC value with thecorrected target value, and incrementing the attenuators in the IFmodule and the attenuator in the RF receive module one at a time toadjust the measured detector value toward the target exact value.
 25. Amethod of operating a wide-range microwave communications unit,comprising controlling attenuators from an IF module and an attenuatorin an RF module together in a closed loop to achieve a desired dynamicresponse, based on stored calibration values in an IF module memory andan RF module memory.
 26. A method of transmitting microwave signalsusing a wide-range transmitter, comprising: receiving control signals ata processor of the transmitter from a signal processing unit, thecontrol signals containing first information including a modulation andfrequency value; retrieving stored calibration values from an IF memoryand an RF memory, the calibration values including attenuation values tobe used during operation of the transmitter; and the processorcontrolling IF circuitry and RF circuitry based on the calibrationvalues and the control signals to attenuate a signal being transmittedat the modulation and frequency value.
 27. The method of claim 26,wherein the RF memory is an EEPROM in an RF module having stored RFcalibration values regarding a detector and attenuator in the transmitRF circuitry, the step of retrieving comprising retrieving the stored RFcalibration values, and the step of controlling further comprisingcontrolling the IF circuitry and RF circuitry based on the calibrationvalues and the control signals to attenuate a signal being upconvertedfor transmission at the modulation and frequency value.
 28. A method ofreceiving microwave signals using a wide-range receiver, comprising:receiving control signals at a processor of the receiver from a signalprocessing unit, the control signals containing first informationincluding a modulation and frequency value; retrieving storedcalibration values from an IF memory and an RF memory, the calibrationvalues including attenuation values to be used during operation of thereceiver; and the processor controlling IF circuitry and RF circuitrybased on the calibration values and the control signals to attenuate asignal being received at the modulation and frequency value.
 29. Aprecalibrated IF module operable in a modular wide-range microwavetransceiver, the IF module comprising: transmit IF circuitry and receiveIF circuitry, and an IF module memory for storing IF calibration valuesfor transmit and receive IF circuitry; a processor and instructions, theprocessor being operably configured to execute the instructions andcoupled to the IF module memory, and a RF transmit module memory and RFreceive module memory, the instructions comprising: transmitinstructions for controlling the transmit IF circuitry and circuitry ofthe RF transmit module based on the IF calibration values and RFtransmit calibration values, and receive instructions for controllingthe receive IF circuitry and circuitry of the RF receive module based onthe IF calibration values and RF receive calibration values.
 30. Aprecalibrated RF module operable in a modular wide-range microwavetransceiver, the RF module comprising one of the group of: aprecalibrated RF (radio frequency) transmit module having an RF transmitmodule memory for storing RF transmit calibration values for circuitryof the RF transmit module, wherein the RF transmit module is operabletogether with a precalibrated transmit IF module having transmit IFcircuitry, an transmit IF module memory for storing transmit IFcalibration values for the transmit IF circuitry, and a transmitprocessor and instructions, the processor being operably configured toexecute the instructions when coupled to the transmit IF module memoryand RF transmit module memory, the instructions comprising transmitinstructions for controlling the transmit IF circuitry and circuitry ofthe RF transmit module based on the transmit IF calibration values andRF transmit calibration values; and a precalibrated RF receive modulehaving an RF receive module memory for storing RF receive calibrationvalues for circuitry of the RF receive module, wherein the RF receivemodule is operable together with a precalibrated receive IF modulehaving receive IF circuitry, an receive IF module memory for storingreceive IF calibration values for the receive IF circuitry, and areceive processor and instructions, the processor being operablyconfigured to execute the instructions when coupled to the receive IFmodule memory and RF receive module memory, the instructions comprisingreceive instructions for controlling the receive IF circuitry andcircuitry of the RF receive module based on the receive IF calibrationvalues and RF receive calibration values.
 31. A modular wide-rangemicrowave receiver comprising: the precalibrated RF transmit module ofclaim 30; the precalibrated RF receive module of claim 30; and aprecalibrated IF module comprising the precalibrated transmit IF moduleand precalibrated RF module, wherein an IF module memory forms both thetransmit and receive IF module memories, and an IF module processorforms both the transmit and receive processors.